1. Field of the Invention
The present invention relates to a semiconductor device and manufacturing method thereof, and more particularly, to a semiconductor device including fins and manufacturing method thereof.
2. Description of the Prior Art
Epitaxial structures are prevalently used in a wide variety of semiconductor applications. For example, the prior art usually forms an epitaxial layer such as an epitaxial silicon germanium (hereinafter abbreviated as SiGe) layer in a single crystal substrate by performing a selective epitaxial growth (hereinafter abbreviated as SEG) method. Because the lattice constant of the epitaxial SiGe layer is larger than that of the silicon substrate, a strain stress is generated to the meta-oxide semiconductor (hereinafter abbreviated as MOS) transistor device. Accordingly, carrier mobility in the channel region is improved and the speed of the MOS transistor device is increased.
Although the epitaxial structures efficiently improve device performance, it increase complexity of the semiconductor fabrication and difficulties of process control. For example, devices of different conductivity types require different stresses: the p-typed transistor devices require compressive stresses while the n-typed transistor devices require tensile stresses. Therefore, it is getting more and more difficult to design and fabricate semiconductor devices demanding different stresses from the epitaxial structures.
Accordingly, though the epitaxial structures are able to improve the device performance, it is always in need to provide semiconductor devices as expected when the progress of semiconductor manufacturing technology is improved and complexity of the products is increased.